1. Field of the Invention
The present invention relates to dispensing systems, and more particularly to dispensers for caustic materials including dissolving means therein and safety provisions therefor.
2. Description of the Prior Art
In commercial applications of washing machines, for example, it is desirable to reduce the cost of detergent and of maintenance time by repeated utilization of a detergent solution until its replacement. During such repeated use, it is occasionally necessary to replenish the solution with an appropriate solution of mixed detergent in order to compensate for drained solution, absorption of grease, oils, solvents, foods and other chemicals.
Early dispensers of the prior art were primarily divided into two classifications. A first class utilized a reservoir of pre-dissolved powdered materials, which, when activated, overflowed concentrated solution into the wash tank. Such systems, however, required an entire package of chemicals to be wetted, thereby releasing some of the active ingredients into the air, or providing for release at uneven rates into the tank. Typical chemicals dispensed by such systems include chlorine, surfactants, light phosphates, and oil surfaced powders.
In such prior art devices, a reservoir was fed by hand, using a scoop to transfer powdered materials from a larger container or from a package which was torn open at the reservoir. For caustic, irritant, or acidic chemicals, however, such replenishment methods provide a hazard of dangerous contact by the operator with the chemical.
A second class of dispensers relates to feeding of dry chemical from a drum by forcing water into the drum, thereby pressurizing a solution outwardly therefrom. Since this system involved the use of pressure and a dependence on the solid connection at the drum, safety of the connection was critical and could not be assured. Moreover, the chemical utilized in the apparatus was wetted prior to its use, thus providing dissipation problems similar to those associated with the above described reservoirs.
Various dispensing devices of the prior art are shown in the following U.S. patents:
Clauson U.S. Pat. No. 1,704,913; Ash U.S. Pat. No. 2,038,260; Forsyth Jr. U.S. Pat. No. 2,062,704; and Lane U.S. Pat. No. Reissue 20,262.
Gatchet U.S. Pat. No. 2,601,672 illustrates dissolution and dispensing of a dry fertilizer, while Klumb U.S. Pat. No. 2,573,576 and Fletcher et al U.S. Pat. No. 2,624,119 disclose further mixing devices.
Dispensers for powdered soap are disclosed in Hall U.S. Pat. No. 874,072; Bohlig U.S. Pat. No. 1,041,417; and Gilmore U.S. Pat. No. 2,520,003.
Harper U.S. Pat. No. 1,653,627 discloses a drinking glass washer, while McDougall U.S. Pat. No. 3,072,137 and Holmes U.S. Pat. No. 3,166,086 provide fluid mixing devices.
None of the above cited art references, however, provide for safety features to avoid the contact between an operator and caustic materials which might be used therein. Such devices, a fortiori, do not provide for duplicated safety systems to assure, in a fail-safe manner, that an operator will not be exposed to such materials. Further, the prior art devices above described do not provide apparatus for maintaining dry chemicals from being prematurely wetted, nor for assuring that an operator need not come in contact with such chemicals during a changeover or replenishment cycle.
In a more recent device of the prior art, however, as disclosed in U.S. Pat. No. 4,063,663 to Larson et al., a dispenser apparatus is provided which includes a curved screen member for retainably supporting a powdered detergent thereabove and which includes a nozzle below the screen. The detergent container forms a part of the dispensing apparatus and includes a door at its top for manual replenishment of the detergent. A safety feature, in the form of a mercury switch, is triggered by opening of the door to disable the nozzle and thus to minimize the possibility of the operator being sprayed by the caustic materials involved. However, in the event that the switch should fail when the operator opens the access door, a hot, caustic solution could easily splash into the operator's face. Moreover, an operator is required to load the caustic materials manually through the access door, and thus must come in contact with the potentially hazardous chemicals. Still further, the access door must be opened in order to determine whether the detergent needs to be replaced or replenished.
The screen in the prior art device presents the potential, under varying water pressure conditions, that free flow of solution may not be permitted, and that, therefore, the chemical might be overwetted or, in situations of low pressure, may not be dissolved. Such uneven results may require increased operator attention and intervention in the operation of the device, thus increasing its cost of operation and furthering the potential of hazardous contact with the chemical utilized therein.